非铝脱氧GCr15轴承钢的夹杂物演变和控制

 铝脱氧轴承钢中常含有较多的D类、Ds类夹杂物,对轴承钢的疲劳性能影响较大。为了减少这类夹杂物,国内某钢厂采用低碱度渣、非铝脱氧的新冶炼思路冶炼轴承钢。对冶炼流程进行了过程取样,使用电镜、夹杂物自动分析系统等方法对夹杂物进行了表征,并研究了夹杂物的演变机理。研究表明,这种轴承钢中的全氧质量分数达到0.000 6%～0.001 0%;冶炼过程中,最先形成以氧化硅为主的夹杂物,在LF精炼过程中不断与钙、镁、铝等成分反应而不断长大,并在RH精炼过程中被去除;最终该钢中夹杂物以小尺寸的硅酸盐为主,尖晶石和钙铝酸盐含量较少。这种冶炼方法改变了轴承钢中的主要夹杂物类型,相对于铝脱氧轴承钢,减少了D类、Ds类夹杂物含量,降低了钢中夹杂物对轴承钢性能的影响。

Inclusions evolution and control of non-aluminum deoxidized GCr15 bearing steel

Aluminum-deoxidized bearing steel often contains D and Ds inclusions, which have a negative influence on the fatigue properties of bearing steel. In order to reduce the content of these kinds of inclusions, a new smelting method with low basicity slag and non-aluminum deoxidization was adopted to smelt bearing steel in a steel mill in China. The whole smelting process was sampled, and the inclusions were characterized by means of SEM-EDS and the automatic inclusion analysis system to clarify the evolution mechanism of inclusions. The results show that the total oxygen content of the bearing steel can reach from 0.000 6% to 0.001 0%; during the smelting process, the inclusions mainly composed of silicon oxide are formed first, which then continuously react with calcium, magnesium, aluminum, and other components in the LF refining process and grow up gradually, and finally are removed in the RH refining process; eventually, the inclusions in the steel are mainly composed of small-size silicate, with few spinel and calcium aluminate. This smelting method changes the main types of inclusions in bearing steel, reduces the content of D and Ds inclusions, and reduces the influence of inclusions on the properties of bearing steel.